In the second season of “Fisica o Chimica” the lives of teachers and students of Zurbaran High School in Madrid are still intertwined inside and outside school.
After the phylosophy teacher was forced to leave her job at the school, Irene and Isaac try and give their relationship a chance, but, unfortunately, it ends miserably.
Irene then starts a relationship with Miguel the new Dramatic Art teacher, who at the same time starts dating a girl named Blanca
Isaac gets consoled by Yoli, who was raped by Oliver. Yoli overcomes her trauma thanks to him and also her friendship with Paula and Cova.
In the meantime, Ruth come out of her coma, caused by the cocaine Gorka offered her.
The girl decides to break their relationship and she is gets closer and closer to Cabano but their relationship makes Gorka mad. Soon, however she will go back to him.
Jan is forced by his parents to marry Xiao-mei which makes Paula very angry. What Paula doesn’t realize is that Jan is becoming increasingly fond of his future wife and he will spend a passionate night with her before the
Julio and Cova’s relationship is suffering so he devotes himself entirely to sport to try and escape his problems. At the gym he meets Rodri with whom he feels immediately in tune.
Fer meets again Carlos, the boy who gave him his first kiss and decides to spend the night with him.
Rocco declares his love to Olimpia, but she refuses his proposal as she thinks he’s doing it only because he believes that he might be the father of her baby she’s expecting.
Clara is removed from her role of principal of the high school and Olimpia, thanks to the help of one of the parents representatives, is elected in her place..
Isaac dies in a quad accident caused by Cabano. His death devastates his friends, his sister Paula, his girlfriend Yoli and above all, Irene, who has never stopped loving him.

After Isaac’s death, students and teachers of Zurbaran High School find it hard to go back to normal.
Paula is still mourning her brother’s loss and Jan’s departure. She takes comfort in Cabano although he is still hiding from her his role in Isaac’s death.
When their relationship ends, the two however decide together to look into the mysterious background of Alma their new classmate.

When Julio begins seeing Lucia, he starts ignoring those closest to him like Fer and Cova, and also embracing the xenophobic and homophobic ideas of his girlfriend and her new nazi friends.
However, when Rodri targets his friend Fer, Julio come to his senses and in an effort to protect his friend, he is seriously injured.
Later he becomes close to Violeta, Irene’s neice, but when the girl asks him to go on vacation together, he feels overwhelmed by a thousand uncertainties.
Fer falls in love with David. Julio’s friend, whose equivocal behavior drives him insane.
Yoli gets infatuated with Quino, a new classmate who charms her immediately. The guy plays in a rock band and he is also deeply Catholic. However, he wants to remain chaist and that’s something that confuses Yoli.
The premature birth of her baby forces Olimpia to miss school. During her absence, the new technology teacher who is particularly strict, replaces her as school principal and this hurts her deeply.
In the meantime, Ruth becomes more and more introvert and develops an eating disorder. When she refuses an inpatient treatment, she seeks Gorka’s support, but Clara tells her to stay away from the girl.

Blanca is caught up once again in a love triangle and she can’t choose between Berto, Yoli’s brother, just got out of prison, and Martin.
Irene is fascinated by Thomas the new English teacher. At first he drifts away but later he comes back to reconquer her.
At the end of the season, someone sets fire to the school. Paula, who initially tries to warn students about the immediate danger, is not believed and is actually classified by the students a compulsive liar.

In the fourth season, the high school Zurbaran reopens its doors.
Blanca has accepted Martin’s marriage proposal and preparations are under way.
Meanwhile Irene, who married Thomas in Vegas during a holiday in America, is not ready to accept her new life so she suggests to him to share a casual relationship.
Although Thomas is not agreeable with that proposal, he accepts the terms his wife gave him. Later, when he finds out that she is engaged in an extramarital affair. he decides to break up with her .
The relationship between Ruth and Cabano, makes their respective exes, Paula and Gorka, very angry and they have sex just to get back at them for their break-up.
Paula gets pregnant by Gorka who initially doesn’t want anything to do with her and the child. But soon, he assumes his responsabilities and shows a completely different side of himself which wins Paula’s heart.
Cabano is diagnosed with cancer. The relationship with Ruth comes to an end when he meets Andrea, during a chemotherapy session and feels very close to her.
Meanwhile, Alma falls in love with Rocco and tries to get him fired from school so she can freely see him.
The art teacher tired of publicly being accused of having a relationship with the student, decides to leave his job. The two start a relationship, but the girl gets tired of him very soon and starts to give all her attention to Quino.
Eva, David’s mother, finds by chance, a picture that shows her son in compromising positions with Fer and shocked, goes to school. He lies to her presenting Yoli as his girlfriend but, in the end, he comes out to his parents.
Eva wants to get her son away from Fer and considers pulling him out of school, then she sends him to see a psycologist who wants to start medical treatment.
When Fer finds out about the extramarital affair between David’s father and Olimpia, he decides to blackmail him hoping that he will leave his son alone.
At first Julio falls in love with Yoli, a love that is not reciprocated by her. Then he realizes to have feelings for Violeta.
However, their relationship is abruptly interrupted by Violeta’s mother who, after having caught them in the act, decides to bring her daughter back home.
At the end of the season, Berto is held liable for having sold alcohol at the high school party, after which Paula has a car accident and is in danger of losing her baby.
Yoli, worried about her brother’s future, considers consulting a lawyer
Finally, right at the moment when Banca and Martin are about to pronunce their fateful “Yes”, the bride to be sees Berto standing at the door of the Church.…